Ignition apparatus



March 14, 1939.

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Patented Mar. 14, 19394 UNITED STATES PATENT OFFICE IGNITION APPARATUS Edward n. Nowosielski, Bloomfield, N. r., assignor to Eclipse Aviation Corporation, a lcorpora.- tion oi New Jersey Application April s, 193s, serial No. 200,527

This invention relates to spark plugs, and particularly to those intended for use under severe conditions as to heat development and current intensity, necessitating maximum eciency in 5 heat dissipation and in electrode construction. This application is composed of subject matter divided out of my applications Serial No. 16,882 led April 17, 1935; Serial No. 29,530, filed July 2, 1935; Serial No. 121,216 led January 18, 1937; Serial No. 146,092 filed Junev2, 1937;

No. 154,845 led July 21, 1937; the

named applications having resulted in Patents 2,088,384 of July 27, 1937; 2,081,500

1937; and 2,109,029 of February 22, 1938, respectively.

Some of the objects are to provide improved electrodes including novel methods of constructing and assembling the electrodes, and of adjusting the spark gap; to provide improved heat deilecting means; and to provi e other improvements and advantageous com inations the nature of which will appear.

These and other objects of the invention will become apparent from inspection of the following specification when read with reference to the accompanying drawings wherein is illustrated the preferred embodiment of the invention. It is to be expressly understood, however, the drawings are for the purpose of illustration only, and are not designed as a definition of the limits of the invention, reference being had to the ap pended claimsfor this purpose.

.In the accompanying drawings forming part hereof Fig. 1 is a'view in elegtion of one embodiment 'i oi' the invention;

Fig. 2 is a longitudinal sectional view of the. plug shown in Fig. 1 but on an enlarged scale;

Fig. 3 is a bottom plan View of certain of the inner elements of the plug as viewed along the plane indicated at 33 in Fig. 2;

Figs. 4 to 8 inclusive, indicate the of the element 86 of Figs. 1 and 2 as it passes through the successive stages in th'e process of forming it into its nal condition.

Fig. 9 is a view in elevation of a second em-l bodiment of the invention;

Fig. 10 is a longitudinal sectional view of the plug shown in Fig. 9 but on an enlarged scale; Fig. 11 is a bottom plan view of the plug of Fig. 9;

Fig. 12 is a sectional view of the central electrode in course of formation; and

Fig. 13 is a diagrammatic view showing an 5 Claims. (Cl. 1235-169) alternative shape for the electrodes I 06 and |09 of Fig. 11.

For the purpose of a shielded aviation spark plug the metal body I of the plug is provided with a shield extension I I which extends upward considerably above the upper end of the spindle I2 to enclose the spindle and the electrical connection between the. same and the conductor which leads the high-tension current to the spindle. This shield extension is preferably in one piece with vthe attaching nut 5, though such unity is not necessary.

Instead of completely 'closing the space between the shield 'extension I I and spindle "I2, I provide a cooling and Ventilating chamber I3in 1.3 the form of an annular space between the shield extension II and a long thin cylindrical metallic sleeve I4 having low thermal conductivity, and lined with a tube I5 formed of rolled mica constituting the wall of a second chamber I6 bounded at its lower end by the compressible metal gland I1, and at its upper end by a novel heat deecting and sealing assembly to be further described. The gland I1, is in contact with the upper end 2i of a sleeve 22 provided for the purpose of absorbing 25 the heat which nds its way into the mica stack I8, and deiiecting said heat to the gland I 'I and outer wall of the plug. Another heat deflecting sleeve 23 is interposed between the base of mica stack I8 and the upper surface oi. an electrode 30 cup 25 secured in position on the base of the spindle I2 by a pressure suiiicient to change the cross-section of the upper end o f the cup (initially of uniform bore as shown in Fig. 12) and cause its contour to conform to that of the spindle base. A heat deecting jacket 24 enclosesvthe spindle I2, and an insert 21 of some metal (such as copper or silver) having high conductivity is inserted within the material steel, preferably-used in the spindle proper. The jacket 24 lis shown as closed at its lower end, but this closure occurs only after the jacket has been positioned upon the spindle, the jacket being initially merely a thin tube open at either and Serial three lirstof May 25,

appearance end. After being placed around the spindle the through the spindle I2 and to deflect the heat flow outwardly and radially into'the copper gland I1 from which much of the heat isdirectly dissipated by the cooling blast circulating adjacent the central' shoulder` 3I of the gland I1, such circulation being produced by reason of the radial openings 32 and the annular chamber 33 communicating therewith. The sleeves 23 and 22 co-act with the jacket 24 in diverting heat from the spindle I2 and the electrode 25 to the annular chamber 34 andthe copper gland I1, and from said chambervand gland to the atmosphere'by way of shell 36 and radial openings 32. In or adjacent the plane of these radial openings 32 there is provided a thrust washer 38 through which pressure is applied to the gland I1, and a compressible washer 39 is provided to insure a firm bond or seal preventing the escape of the confined cylinder gases, the pressure being applied to thesaid elements I1 and 39 through thrust washer 38 as a result of threadingr' the shield extension II into the shell I0, the two elements just mentioned being correspondingly threaded as indicated at 4I.

As shown clearly in Fig. 2, the spindle I2 is of reduced diameter at two or more points as indicated at 43 and 44; and the jacket 24, the rolled mica tube 46, and the soft metal gland I1 are pressed snugly against these peripheral depressions in the spindle as one of the plug assembling operations. This operation of applying pressure laterally results not only in a firm seal around the spindle I2 but also eliminates 'any longitudinally extending crevices or pipes which have heretofore been a source of leakage characteristic of rolled mica insulating tubes. The wrapping-of the mica sheets one around the other tends to leave such crevi'ces running longitudinally of the wrapping, but by producing kinks at several points along the length of the wrapping, as indicated, I have found it possible to eliminate this source of trouble.

As a means of maintaining the mica stack 48 in the compressed condition and at the same time applying radial pressure to hold the mica lining I of the inner metallic sleeve I4 in position, and at the same time effecting an additional path for the transfer of heat directly to the said sleeve I4 from which it may be radiated to the atmosphere by the cooling current of air flowing along the chamber I3 and the radial apertures 20 and 26, I propose to thread the upper end 5I of the spindle I2 and apply to said threaded portion 5I a pair of threaded collars or nuts 52 and 53, the latter having an external taper to receive a correspondingly internally tapered gland 54 of softer material such as copper so that it may, when subjected to the pressure applied by the tighten ing of nut 52, form a firm bond with the washer 56 and also with the expansion ring 58 which grips the mica lining I5 at a point approximately midway' between its ends, this lining 58 being inserted and expanded in the tube I4 prior to the assembly of said tube within the shield extension I I. -The associated elements 52,. 53, 54 and 56, on the other hand, are rst assembled separately in position upon the inner plug assembly, and the latter is then dropped in place within the shell 36 prior to bringing the shield -extension assembly into position, Alsd prior to attaching the upper assembly there is inserted Within the hollowed portion of the spindle, a coil spring 6I and a contact pin 62 having a circumferential shoulder 63 against which the upper end of the spring 6I abuts to urge said pin upwardly into position to contact the radially spread strands of the current conducting wire 66 when the latter is installed in place. Associated with the wire 66 is its covering 61 of insulating material, its outer metallic sheath 68, the swivel connection 69 soldered or otherwise secured thereto, and the attached coupling nut 1I, all of which are brought.

into assembled relationship with the parts previously described.

As noted above, the inner end of the conductor 66 extends below the insulating material 61 for a certain distance so that the strands may be spread apart to provide better contact with the end o f the pin 62. The method of fastening the spread apart ends of the conductor is preferably the same as in my Patent No. 2,108,504 and includes the provision of a at metallic plate 13 having a pair of notches 14 and 15 (Fig. 3) out therein on opposite sides of the central aperture 16 through which the conductor 66 passes. Each of the spread apart sections of the stranded conductor is inserted into position Within each of the slots 14 and 15 and thereupon the plate 13 is pinched at either end to partially close the slots, the slot 15 peing shown in the partially closed position which it assumes after the pinching operation. The cable and plate 13 are then held in the assembled relation indicated in Fig. 2 by the provision of a retainer or spacer sleeve 11 of insulating material such as porcelain, glass or Bakelite, the upper end of the spacer 11 terminating in the plane of the lower surface of the swivel member 63. Also the upper outer surface of the spacer 11 is in contact with the inwardly and downwardly turned end of aferrule 19 of low thermal conductivity, the outer portion of which rests upon the shoulder 8| formed near the upper end of the heat dissipating inner Wall I4 of the shieldextension assembly.

As above indicated, one of the important features of the invention concerns the outer or grounded electrode and the method of its manufacture and installation. 'Ihe rst step is to secure an H-shaped metallic piece 86 of suitable heat and spark resisting qualities While at the same time a sufliciently good conductor. Such a piece is indicated in Fig. 4. 'Ihis piece is then subjected to a bending operation to bring it into substantially the form indicated in Fig. 5. Next the parallel sides 81 and 88 are turned into semicircular arcs which preferably do not quite join (as indicated in Figs. 6 and '1) the cross-connecting portion remaining in the form to which it is initially bent, as shown in Fig. 5. The final step in formation of the electrode is to shape the upper annular surface formed by the semi-circular parts 81 and 88 so that in transverse section it will have the final appearance indicated) in Fig. 2. When thus completed the electrode receives a thin dished Washer 9| of soft metal such as copper and then asecond dished washer 92v of harder vmaterial and preferably the same material as the electrode 86 itself. The installation and completion of the electrode assembly is then obtained in the following manner: 'I'he shell 36 is placed on a table or work-bench with its lower counterbore 94 uppermost, a thin cup-shaped liner 95 of soft metal, preferably the same lmaterial as tion within the inverted cup member 95 and the assembly consisting of the parts 36, 95, 92 and 86, is then placed in a hydrogen gas furnace or other suitable heat chamber and subjected to a temperature sufcient to cause a fusion or welding along the surfaces of the elements 95 and 9|, with the result that the five elements above enumerated become fused into a permanently welded single unit. This unit is then removed from the furnace, the core assembly, the shield extension assembly, and upper cable' assemblies successively attached thereto in the respective manners above indicated. When this complete assembly has been accomplished it will be found that the inner electrode 25 occupies a position approaching that of the transverse portion 86 of the outer electrode and also approaching that of the inner cylindrical edge 99 of the thimble 92, forming an auxiliary spark gap, the clearances therebetween being such that the spark will normally jump from the relatively broad surface of the electrode 25 to the correspondingly broad plane surface of the cross-piece 86 of the ground electrode; but if for any reason this normal path of the spark is obstructedas for example by the formation of ice particles-the spark can then jump from the cylindrical surface of the electrode 25 to the above described cylindrical surface 99 of the thimble 92 which may therefore be considered as a part of the completed electrode. In fact, it is, of course, possible to have the elements 92, 9| and 86 originally formed as an integral whole rather than being composed of three subsequently united pieces as shown.

It will be noted that the mica tube 46 terminates somewhat above the lower flange of the heat conducting sleeve 23 of copper or other metal, and that therefore a plurality of the mica-disks I8 lie between the end of the mica tube and the said flanged portion of the sleeve.

This arrangement has the advantage of facilitating maximum heat transfer from the mica assembly I8 and defiecting such heat to the jacket 24 as well as to the sleeve 22, and at the same time provides a better degree of protection of the lower ends of the layers constituting the completed tube 46. It will also be observed that the cylindrical portion of the sleeve 23 is externally tapered to facilitate a snug grip and seal between parts 46, 23 and 24.

i In the second embodiment of the invention, as shown'in Figs. 9 to 11 inclusive, there are many elements which are identical in their structure, arrangement, and functioning, to the elements designated by corresponding reference characters in Figs. 1 to 3 inclusive, and these corresponding elements will be recognized without further detailed description thereof. There are, however, certain differences which are now to be described. In this second embodiment the central spindle I2 terminates within an electrode |06 whose outer surface has an elliptical contour, as indicated best in Fig. 11, While the cooperating parallel walls |01 and |08 of the outer electrode |09 form a parallelogram as viewed in Fig. 11; but in place of a true elliptical contour for the part |06, as shown in Fig. l1, the contour may be a combination of arcs and parallel edges as shown at 206 in Fig. 13. Either arrangement permits ready adjustment of the spark gap by producing relative angular motionbetween the parts |06 and |09 (or 206 and 209) 4about the common axis of said parts. This adjustment can be effected by inserting in the space between the two elements a gage 'of proper thickness to give the desired 4spark clearance and then applying said gage to the elements as a lever to cause one of said elements to turn suficiently to produce the desired clearance therebetween. Electrode |09 is integrated with the recessed end 94 of the shell 36 by fusing or bonding it thereto through the instrumentality of ajoining piece III of a soft metal similar to that of the sleeve 95 which bonds electrode 86 to the -shell in Fig'. 2.

Gland I1 of Fig. 10rhas la tapered surface for registry with a correspondingly tapered seat ||4 in the shell 36, and therefore differs structurally in this respect from the gland I1 of Fig. 2-this structural difference making use of the gasket 39 of Fig. 2 unnecessary. Functionally, however, it is the equivalent of the gland I'I of Fig. 2 and is adapted to be pressed rmly against the shell to insure a sealing of the plug at this point in response to the application of pressure thereto through the agency of the thrust washer 38 which is the structural and functional counterpart of the thrust washer 38 of Fig. 2. Also in its heat dissipating action the gland I1 of Fig. 10 is comparable to the gland I1 of Fig. 2, in that it c0- operates with the metallic rods I9 in accelerating heat flow outwardly to the shell 36.

Other features differentiating the structure of Fig. 10 from that of Fig. 2 include the baiile II3 of heat flow resisting material such as asbestos, and the pedestal I|1 of current conducting carborundum, stainless steel or the like, having low heat conductivity to further reduce the amount of heat entering contact spring 6| which maintains the electrode pin 62 in contact with the conductor 66. In this embodiment cable spacer 'I1 is free to move upwardly beyond rim I I8 of member 83, but only to the point of contact with the annular rim I8 on the swivel member |69. The said member I 69 is internally threaded to receive a correspondingly threaded gland |2| of steel or similar material to firmly grip the inwardly turned end |22 of ametallic corrugated tube |23 which, by reason of the pressure exerted thereupon by the application of the nut |2I, is pressed firmly upon the beveled annular seat |24 of a bonding member |25, constituting the means for providing a firm electrical bond between the shielding elements |23 and |69, the latter being in rm contact with the complemen-l tary shielding element by reason of the pressure exerted thereupon by the act of tightening the coupling nut 1| threaded to the upper end of the shield extension I I. This nut 1| is shown at 10 (Figs. 9 and l0) as milled out horizontally and also vertically to increase the effectiveness of the hold. 'I'his milling provides flexibility which facilitates establishment of a locked connection by the exertion of inward pressure upon the open ends. In Figs. l and 2 the milling is horizontal only, as indicated at 10', but the purpose is the same.

What is claimed is:-

1. In a .spark plug, the combination with a central spindle terminating in an electrode of elliptical contour, of an enclosing shell provided with a cooperating electrode having a. plurality of rectilinear edges adjustably spaced from said elliptical electrode.

2. In a spark plug, the combination with a central spindle having a relatively thin crosssection and a base of larger cross-sectional dimensions, of .a cup-shaped electrode fitting over said base and extending above said base for a `sumclen't distance to facilitate integration with said spindle by the application of pressure to the open end of the cup to cause said open end to close in against the thinner section of the spindle immediately above said base, and therefore become undetachable therefrom.

3. In a spark plug, the combination with a central spindle having a relatively thin crosssection and a base of larger cross-sectional dimensions, of a cup-shaped electrode tting over said base and extending above said base for a suiicient distance to facilitate integration with said spindle by the application of suiiicient pressure to the open end of the cup to cause said open end to close in against the thinner section of the spindle immediately above said base, and therefore become undetachable therefrom, and a layer oi' fusible metal interposed between said cup and said spindle to act as a fusing agent therebetween upon application of heat thereto. n

4. In a spark plug, the combination with a central spindle terminating in any electrode of elliptical contour, of an enclosing shell provided with a cooperating electrode having a plurality of edges adjustabiy spaced from said elliptical electrode. 4 l

5. In a spark plug, the combination with a central spindle terminating in an electrode of elliptical contour, of an enclosing shell provided with a cooperating electrode adjustably spaced from said elliptical electrode.

EDWARD B. NOWOSIELSKI. 

